BACKGROUND Aorto-hepatic conduits(AHCs)are an effective revascularization method for liver allografts when the native hepatic artery is unusable.Various studies have confirmed that outcomes with AHCs are inferior to t...BACKGROUND Aorto-hepatic conduits(AHCs)are an effective revascularization method for liver allografts when the native hepatic artery is unusable.Various studies have confirmed that outcomes with AHCs are inferior to those with native hepatic artery inflow.AIM To investigate the published evidence on the outcomes according to different inflow site for AHCs.METHODS A systematic search was conducted for studies reporting on AHCs in liver transplantation over the last 10 years(January 2014 onwards).Two independent reviewers selected articles,assessed quality,and evaluated bias in the included systematic reviews.The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale.The protocol was registered with PROSPERO(CRD42024545810).Review was conducted using the Preferred Reporting Items for Systematic Review and Meta-Analysis statement standards.RESULTS Fourteen studies identified a total of 32486 deceased donor liver transplants,of which 1136(3.5%)required AHCs.The most frequent indications for AHC use included poor arterial flow,intimal dissections,and hepatic artery thrombosis.Among all AHCs,207(18.2%)were supra-coeliac(SC)AHCs,738(65.0%)infrarenal(IR)AHCs,25(2.2%)iliac artery conduits,and 166(14.6%)had unspecified origins.Pooled analysis revealed comparable demographic characteristics.The median follow-up duration ranged from 18 to 52 months.There were no significant differences in early occlusions of AHCs[odds ratio(OR)=0.94(0.48,1.84);P=0.86],late occlusions of AHCs[OR=0.46(0.16,1.32);P=0.15],early allograft dysfunction[OR=0.82(0.46,1.47);P=0.51],biliary complications[OR=1.10(0.69,1.76);P=0.68],post-transplant renal replacement therapy(RRT)requirement[OR=1.12(0.72,1.72);P=0.62],and major surgical complications(Clavien-Dindo>3b)[OR=1.06(0.70,1.61);P=0.79].The median duration for graft occlusion was approximately 142 days,ranging from 13 to 3313 days.One-year graft and patient survival rates for SC conduits were 77%to 81.1%and 80%to 85.1%,respectively.For IR conduits,one-year graft and patient survival rates were 66%to 79.1%and 73%to 88.3%,respectively.Five-year graft and patient survival rates for SC conduits were 53.9%to 67%and 67.8%to 74%,respectively.For IR conduits,five-year graft and patient survival rates were 50%to 56%and 56%to 64.9%,respectively.CONCLUSION Considering these findings,there is no significant difference in early and late outcomes between SC and IR AHCs,although there is a discernible tendency towards higher late occlusion rates in the IR group.展开更多
The flow field characteristics of the conduit-matrix system(CMS)have consistently been a primary area of interest to researchers.However,under the long-term influence of water flow,the hydraulic conductivity of the ma...The flow field characteristics of the conduit-matrix system(CMS)have consistently been a primary area of interest to researchers.However,under the long-term influence of water flow,the hydraulic conductivity of the matrix surrounding the conduit often deforms differentially along the conduit axis,resulting in the development of a conduit-multilayer matrix system(CMMS).This renders conventional models inadequate in accurately describing the flow field characteristics of CMMS.In this study,a semi-analytical model with second-order accuracy is developed to investigate the velocity profile characteristics of CMMS by coupling the Navier-Stokes(N–S)equations in the conduit and the Darcy-Brinkman(D-B)equation in the multilayer matrices.In this model,the interface between the conduit and the matrix satisfies the velocity continuity and stress jumping condition.In contrast,different matrix interfaces require both velocity and stress to be equal.The model's validity is verified through Lattice Boltzmann Method(LBM)simulation,COMSOL simulation,and experimental data under different conduit apertures,matrix region numbers,and matrix permeability characteristics.Moreover,the current model predicts discharges with higher accuracy than the Hagen-Poiseuille law and Darcy's law(the maximum error between the present model and the test is 7.24%).Furthermore,the existing Poiseuille's law,conduit-matrix model,and conduit-matrix1-matrix2 model are all special cases of the current semi-analytical model,thereby indicating its broader applicability.Sensitivity results reveal that the flow velocities in the surrounding matrix and the conduit regions also increase when the permeability of the matrix in proximity to the conduit increases.Additionally,as the stress jumping coefficient at the interface approaches zero,the transition from free flow to seepage becomes smoother.展开更多
Objective Peripheral nerve injury leads to various degrees of functional defects.Nerve guidance conduits are considered as a new promising scaffold for peripheral nerve repair.However,conventional single-material nerv...Objective Peripheral nerve injury leads to various degrees of functional defects.Nerve guidance conduits are considered as a new promising scaffold for peripheral nerve repair.However,conventional single-material nerve conduits have shown limited efficacy in protecting cells from posttraumatic inflammation.This study aims to develop a single-process PLGA-based nerve conduit loaded with melatonin to enhance the biological performance of pure PLGA materials by suppressing oxidative stress and inflammatory responses.Methods The PLGA conduit is prepared with dry-jet wet spinning methods.The melatonin is integrated into PLGA conduits directly with the single-step process.Scanning electrical microscope observation,FTIR test,degradation test and drug releasing test were performed to characterize the morphology and physical properties of the nerve conduits.Schwann cells were cultured to test the biocompatibility of the prepared nerve conduits.Oxidative stress was applied on Schwann cell using hydrogen peroxide.Then the protecting effects of the nerve conduits were tested on the hydrogen peroxide-treated cells.SD rat sciatic model was applied to test the conduit in vivo.Results The melatonin is successfully integrated into the nerve conduit with the dry-jet wet spinning method.Cell adhesion and proliferation test of the Schwann cell indicated that the nerve conduits exhibit excellent biocompatibility.While the mitochondrial morphology observation and JC-1 potential detection also showed protecting effects on Mitochondria.The q-PCR analysis showed nerve conduits reduced cellular oxidative stress and inflammatory responses while enhancing cellular proliferation.A marked enhancement on SD rat sciatic nerve regeneration was also observed on melatonin loaded conduits.Conclusions By integrating melatonin into PLGA using the dryjet wet-spinning technique,the conduit is endowed with multiple functional advantages,including antiinflammatory,antioxidant,and neuroprotective properties.This approach is expected to create a favorable microenvironment for nerve tissue regeneration and provide a new perspective for the treatment of peripheral nerve injuries.展开更多
The flow patterns in the inlet and outlet conduits have a decisive effect on the safe, stable, and highly efficient operation of the pump in a large pumping station with low head. The numerical simulation of three-dim...The flow patterns in the inlet and outlet conduits have a decisive effect on the safe, stable, and highly efficient operation of the pump in a large pumping station with low head. The numerical simulation of three-dimensional （3D） turbulence flow in conduits is an important method to study the hydraulic performance and conduct an optimum hydraulic design for the conduits. With the analyses of the flow patterns in the inlet and outlet conduits, the boundary conditions of the numerical simulation for them can be determined. The main obtained conclusions are as follows： （i） Under normal operation conditions, there is essentially no pre-swirl flow at the impeller chamber inlet of an axial-flow pump system, based on which the boundary condition at the inlet conduit may be defined. （ii） The circulation at the guide vane outlet of an axial-flow pump system has a great effect on the hydraulic performance of the outlet conduit, and there is optimum circulation for the performance. Therefore, it is strongly suggested to design the guide vane according to the optimum circulation. （iii） The residual circulation at the guide vane outlet needs to be considered for the inlet boundary condition of the outlet conduit, and the value of the circulation may be measured in a specially designed test model.展开更多
Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（...Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（lactic-co-glycolic acid） （PLGA） copolymer to construct a three-dimensional （3D） bionic nerve conduit, with two channels and multiple microtubule lumens, and incorporating two neurotrophic factors, each with their own delivery system, as a novel environment for peripheral nerve regeneration. The efficacy of this conduit in repairing a 1.5 cm sciatic nerve defect was compared with PLGA-alone and PLGA-microfilament conduits, and autologous nerve transplantation. Results showed that compared with the other groups, the 3D bionic nerve conduit had the fastest nerve conduction velocity, largest electromyogram amplitude, and shortest electromyogram latency. In addition, the nerve fiber density, myelin sheath thickness and axon diameter were significantly increased, and the recovery rate of the triceps surae muscle wet weight was lowest. These findings suggest that 3D bionic nerve conduits can provide a suitable microenvironment for peripheral nerve regeneration to efficiently repair sciatic nerve defects. p展开更多
The relationship between the head loss and the discharge and circulation of the conduit of a pump system with low head is an important problem with an obvious influence on the improvement of its hydraulic performance....The relationship between the head loss and the discharge and circulation of the conduit of a pump system with low head is an important problem with an obvious influence on the improvement of its hydraulic performance. The velocity circulation from the pump guide vane makes the relationship more complicated, which has to be understood comprehensively. The results indicate that, under the condition of zero circulation, the head loss of the inlet and outlet conduits is in proportion to the square of discharge. Under the condition that the Reynolds number is satisfied with the resistant square area, the conduit loss is in proportion to the square of discharge for the similar working points with different speeds in a certain rotational speed range, indicating that the pump system efficiency is constant. The outlet conduit loss of design discharge for a pump system with low head depends on the velocity circulation from the guide vane exit, and the relationship between the loss and the circulation is an open curve with an upward direction, meaning that there is an optimal circulation for the loss. Under the condition of various working points for a pump system with low head, the head loss of the outlet conduit is under the cross influence of both the discharge and the circulation. As a result, the relationship between the head loss and the discharge is almost linear, and the mechanism needs to be further studied.展开更多
Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduit...Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.展开更多
Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the ...Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.展开更多
BACKGROUND Type 2 diabetes(T2D)remission has been widely reported after bariatric surgery,but rarely reported after esophagectomy.AIM To explore the incidence and predictors of T2D remission 1 year after esophagectomy...BACKGROUND Type 2 diabetes(T2D)remission has been widely reported after bariatric surgery,but rarely reported after esophagectomy.AIM To explore the incidence and predictors of T2D remission 1 year after esophagectomy with gastric conduit reconstruction.METHODS In this prospective study,consecutive patients from 2 tertiary hospitals who had esophageal cancer and T2D and underwent esophagectomy with gastric conduit reconstruction were studied preoperatively and at 3 months,6 months,and 12 months postoperatively.Remission of T2D is defined as glycated hemoglobin(HbA1c)values below 6.5%without glucose-lowering medications.Related clinical information were recorded and analyzed.RESULTS A total of 187 patients were included.Of these patients,24(12.8%)discontinued antidiabetic drugs and maintained HbA1c values below 6.5%1 year after surgery.At baseline,patients with T2D remission were younger(63.0±5.2 years vs 67.0±6.1 years,P=0.002),had higher body mass index values(body weight 68.6±11.1 kg vs 61.2±9.3 kg,P=0.001;body mass index 25.5±2.4 kg/m2 vs 23.8±3 kg/m2,P=0.011),shorter duration of T2D(4.9±3.9 years vs 7.1±3.7 years,P=0.008)and higher preoperative HbA1c(8.5%±1.7%vs 7.7%±1.3%,P=0.042).Multivariate logistic regression analysis showed that younger age and greater body weight were independent predictors of T2D remission after surgery.CONCLUSION This study reveals a significant incidence of T2D remission after esophagectomy with gastric conduit reconstruction,and remission is more frequent in patients with younger age and greater body weight.展开更多
Traumatic peripheral nerve injuries are a major contributor to long-term disability,accounting for nearly half of all peripheral nervous system disorders.Although autologous nerve grafting remains the clinical gold st...Traumatic peripheral nerve injuries are a major contributor to long-term disability,accounting for nearly half of all peripheral nervous system disorders.Although autologous nerve grafting remains the clinical gold standard,it is limited by donor-site morbidity and often fails to achieve full functional recovery.Biodegradable collagen conduits have emerged as an appealing alternative,providing a scaffold for directed axonal growth without requiring graft harvest.We reported three cases of chronic nerve injuries(6-12 months post-trauma):two involving 2.0-3.5 cm ulnar nerve defects in the forearm and one with a 2.5 cm median nerve defect at the wrist.Under microscopic guidance,each defect was bridged with a tubular type I collagen conduit secured by epineurial sutures,followed by standardized physiotherapy and sensory reeducation.At 12-18 months of follow-up,all patients demonstrated near-complete sensory recovery—two-point discrimination and Semmes-Weinstein thresholds returned to≤6 mm—and motor function improved to Medical Research Council grades 4-5,restoring fine dexterity and grip strength.Patient-reported measures indicated marked reductions in neuropathic pain and paresthesia.No conduit-related adverse events or neuroma formation were observed.This case series highlights the potential of collagen-based conduits to promote robust axonal regeneration and functional restoration even in delayed presentations.By eliminating donor-site morbidity and simplifying the reconstructive procedure,conduit-assisted repair offers a less invasive,reproducible alternative to autologous grafts for both acute and chronic peripheral nerve injuries.展开更多
Microspheres containing nerve growth factor for sustained release were prepared by a compound method, and implanted into chitosan conduits to repair 10-mm defects on the right buccal branches of the facial nerve in ra...Microspheres containing nerve growth factor for sustained release were prepared by a compound method, and implanted into chitosan conduits to repair 10-mm defects on the right buccal branches of the facial nerve in rabbits. In addition, chitosan conduits combined with nerve growth factor or normal saline, as well as autologous nerve, were used as controls. At 90 days post-surgery, the muscular atrophy on the right upper lip was more evident in the nerve growth factor and normal sa- line groups than in the nerve growth factor-microspheres and autologous nerve groups. Electro- physiological analysis revealed that the nerve conduction velocity and amplitude were significantly higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. Moreover, histological observation illustrated that the di- ameter, number, alignment and myelin sheath thickness of myelinated nerves derived from rabbits were higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. These findings indicate that chitosan nerve conduits com- bined with microspheres for sustained release of nerve growth factor can significantly improve facial nerve defect repair in rabbits.展开更多
The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data com...The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data comparing the biomechanical factors related to the sciatic nerve are available. In the present study, rabbit models of 10-mm sciatic nerve defects were prepared. The rabbit models were repaired with autologous nerve, a polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells, or a polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel. After 24 weeks, mechanical testing was performed to determine the stress relaxation and creep parameters. Following sciatic nerve injury, the magnitudes of the stress decrease and strain increase at 7,200 seconds were largest in the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel group, followed by the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells group, and then the autologous nerve group. Hematoxylin-eosin staining demonstrated that compared with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells group and the autologous nerve group, a more complete sciatic nerve regeneration was found, including good myelination, regularly arranged nerve fibers, and a completely degraded and resorbed conduit, in the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel group. These results indicate that bridging 10-mm conduit ＋ bone marrow mesenchymal stem sciatic nerve defects with a polylactic glycolic acid cells ＋ extracellular matrix gel construct increases the stress relaxation under a constant strain, reducing anastomotic tension. Large elongations under a constant physiological load can limit the anastomotic opening and shift, which is beneficial for the regeneration and functional reconstruction of sciatic nerve. Better regeneration was found with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel grafts than with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells grafts and the autologous nerve grafts.展开更多
The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposi...The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposits; （2） fractional crystallization and crustal contamination, particularly the input of sulfur from crustal rocks, resulting in sulfide immiscibility and segregation; and （3） the timing of sulfide concentration in the intrusion. The super-large magmatic Ni-Cu sulfide deposits around the world have been found in small mafic-ultramafic intrusions, except for the Sudbury deposit. Studies in the past decade indicated that the intrusions hosting large and super-large magmatic sulfide deposits occur in magma conduits, such as those in China, including Jinchuan （Gansu）, Yangliuping （Sichuan）, Kalatongke （Xinjiang）, and Hongqiling （Jilin）. Magma conduits as open magma systems provide a perfect environment for extensive concentration of immiscible sulfide melts, which have been found to occur along deep regional faults. The origin of many mantle-derived magmas is closely associated with mantle plumes, intracontinental rifts, or post-collisional extension. Although it has been confirmed that sulfide immiscibility results from crustal contamination, grades of sulfide ores are also related to the nature of the parental magmas, the ratio between silicate magma and immiscible sulfide melt, the reaction between the sulfide melts and newly injected silicate magmas, and fractionation of the sulfide melt. The field relationships of the ore-bearing intrusion and the sulfide ore body are controlled by the geological features of the wall rocks. In this paper, we attempt to demonstrate the general characteristics, formation mechanism,tectonic settings, and indicators of magmatic sulfide deposits occurring in magmatic conduits which would provide guidelines for further exploration.展开更多
The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph-eral nerve injury are better than in the traditional epineurium suture,so it is possible to replace the epineurium sutu...The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph-eral nerve injury are better than in the traditional epineurium suture,so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury.This study sought to identify the regeneration law of nerve fibers in the biological conduit.A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit.The results showed that the biological conduit had good his-tocompatibility.Tissue and cell apoptosis in the conduit apparently lessened,and regenerating nerve fibers were common.The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture.During the prime period for nerve fiber regeneration(2-8 weeks),the number of Schwann cells and nerve fibers was higher in both proximal and distal ends,and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture.The above results provide an objec-tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.展开更多
In recent years, the use of Schwann cell transplantation to repair peripheral nerve injury has attracted much attention. Animal-based studies show that the transplantation of Schwann cells in combination with nerve sc...In recent years, the use of Schwann cell transplantation to repair peripheral nerve injury has attracted much attention. Animal-based studies show that the transplantation of Schwann cells in combination with nerve scaffolds promotes the repair of injured peripheral nerves. Autologous Schwann cell transplantation in humans has been reported recently. This article reviews current methods for removing the extracellular matrix and analyzes its composition and function. The development and secretory products of Schwann cells are also reviewed. The methods for the repair of peripheral nerve injuries that use myelin and Schwann cell transplantation are assessed. This survey of the literature data shows that using a decellularized nerve conduit combined with Schwann cells represents an effective strategy for the treatment of peripheral nerve injury. This analysis provides a comprehensive basis on which to make clinical decisions for the repair of peripheral nerve injury.展开更多
文摘BACKGROUND Aorto-hepatic conduits(AHCs)are an effective revascularization method for liver allografts when the native hepatic artery is unusable.Various studies have confirmed that outcomes with AHCs are inferior to those with native hepatic artery inflow.AIM To investigate the published evidence on the outcomes according to different inflow site for AHCs.METHODS A systematic search was conducted for studies reporting on AHCs in liver transplantation over the last 10 years(January 2014 onwards).Two independent reviewers selected articles,assessed quality,and evaluated bias in the included systematic reviews.The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale.The protocol was registered with PROSPERO(CRD42024545810).Review was conducted using the Preferred Reporting Items for Systematic Review and Meta-Analysis statement standards.RESULTS Fourteen studies identified a total of 32486 deceased donor liver transplants,of which 1136(3.5%)required AHCs.The most frequent indications for AHC use included poor arterial flow,intimal dissections,and hepatic artery thrombosis.Among all AHCs,207(18.2%)were supra-coeliac(SC)AHCs,738(65.0%)infrarenal(IR)AHCs,25(2.2%)iliac artery conduits,and 166(14.6%)had unspecified origins.Pooled analysis revealed comparable demographic characteristics.The median follow-up duration ranged from 18 to 52 months.There were no significant differences in early occlusions of AHCs[odds ratio(OR)=0.94(0.48,1.84);P=0.86],late occlusions of AHCs[OR=0.46(0.16,1.32);P=0.15],early allograft dysfunction[OR=0.82(0.46,1.47);P=0.51],biliary complications[OR=1.10(0.69,1.76);P=0.68],post-transplant renal replacement therapy(RRT)requirement[OR=1.12(0.72,1.72);P=0.62],and major surgical complications(Clavien-Dindo>3b)[OR=1.06(0.70,1.61);P=0.79].The median duration for graft occlusion was approximately 142 days,ranging from 13 to 3313 days.One-year graft and patient survival rates for SC conduits were 77%to 81.1%and 80%to 85.1%,respectively.For IR conduits,one-year graft and patient survival rates were 66%to 79.1%and 73%to 88.3%,respectively.Five-year graft and patient survival rates for SC conduits were 53.9%to 67%and 67.8%to 74%,respectively.For IR conduits,five-year graft and patient survival rates were 50%to 56%and 56%to 64.9%,respectively.CONCLUSION Considering these findings,there is no significant difference in early and late outcomes between SC and IR AHCs,although there is a discernible tendency towards higher late occlusion rates in the IR group.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52079068,52090081)the State Key Laboratory of Hydroscience and Engineering(Grant No.2021-KY-04).
文摘The flow field characteristics of the conduit-matrix system(CMS)have consistently been a primary area of interest to researchers.However,under the long-term influence of water flow,the hydraulic conductivity of the matrix surrounding the conduit often deforms differentially along the conduit axis,resulting in the development of a conduit-multilayer matrix system(CMMS).This renders conventional models inadequate in accurately describing the flow field characteristics of CMMS.In this study,a semi-analytical model with second-order accuracy is developed to investigate the velocity profile characteristics of CMMS by coupling the Navier-Stokes(N–S)equations in the conduit and the Darcy-Brinkman(D-B)equation in the multilayer matrices.In this model,the interface between the conduit and the matrix satisfies the velocity continuity and stress jumping condition.In contrast,different matrix interfaces require both velocity and stress to be equal.The model's validity is verified through Lattice Boltzmann Method(LBM)simulation,COMSOL simulation,and experimental data under different conduit apertures,matrix region numbers,and matrix permeability characteristics.Moreover,the current model predicts discharges with higher accuracy than the Hagen-Poiseuille law and Darcy's law(the maximum error between the present model and the test is 7.24%).Furthermore,the existing Poiseuille's law,conduit-matrix model,and conduit-matrix1-matrix2 model are all special cases of the current semi-analytical model,thereby indicating its broader applicability.Sensitivity results reveal that the flow velocities in the surrounding matrix and the conduit regions also increase when the permeability of the matrix in proximity to the conduit increases.Additionally,as the stress jumping coefficient at the interface approaches zero,the transition from free flow to seepage becomes smoother.
文摘Objective Peripheral nerve injury leads to various degrees of functional defects.Nerve guidance conduits are considered as a new promising scaffold for peripheral nerve repair.However,conventional single-material nerve conduits have shown limited efficacy in protecting cells from posttraumatic inflammation.This study aims to develop a single-process PLGA-based nerve conduit loaded with melatonin to enhance the biological performance of pure PLGA materials by suppressing oxidative stress and inflammatory responses.Methods The PLGA conduit is prepared with dry-jet wet spinning methods.The melatonin is integrated into PLGA conduits directly with the single-step process.Scanning electrical microscope observation,FTIR test,degradation test and drug releasing test were performed to characterize the morphology and physical properties of the nerve conduits.Schwann cells were cultured to test the biocompatibility of the prepared nerve conduits.Oxidative stress was applied on Schwann cell using hydrogen peroxide.Then the protecting effects of the nerve conduits were tested on the hydrogen peroxide-treated cells.SD rat sciatic model was applied to test the conduit in vivo.Results The melatonin is successfully integrated into the nerve conduit with the dry-jet wet spinning method.Cell adhesion and proliferation test of the Schwann cell indicated that the nerve conduits exhibit excellent biocompatibility.While the mitochondrial morphology observation and JC-1 potential detection also showed protecting effects on Mitochondria.The q-PCR analysis showed nerve conduits reduced cellular oxidative stress and inflammatory responses while enhancing cellular proliferation.A marked enhancement on SD rat sciatic nerve regeneration was also observed on melatonin loaded conduits.Conclusions By integrating melatonin into PLGA using the dryjet wet-spinning technique,the conduit is endowed with multiple functional advantages,including antiinflammatory,antioxidant,and neuroprotective properties.This approach is expected to create a favorable microenvironment for nerve tissue regeneration and provide a new perspective for the treatment of peripheral nerve injuries.
基金Project supported by the Natural Science Foundation of Jiangsu Higher Education Institutions ofChina(No.12KJD570001)
文摘The flow patterns in the inlet and outlet conduits have a decisive effect on the safe, stable, and highly efficient operation of the pump in a large pumping station with low head. The numerical simulation of three-dimensional （3D） turbulence flow in conduits is an important method to study the hydraulic performance and conduct an optimum hydraulic design for the conduits. With the analyses of the flow patterns in the inlet and outlet conduits, the boundary conditions of the numerical simulation for them can be determined. The main obtained conclusions are as follows： （i） Under normal operation conditions, there is essentially no pre-swirl flow at the impeller chamber inlet of an axial-flow pump system, based on which the boundary condition at the inlet conduit may be defined. （ii） The circulation at the guide vane outlet of an axial-flow pump system has a great effect on the hydraulic performance of the outlet conduit, and there is optimum circulation for the performance. Therefore, it is strongly suggested to design the guide vane according to the optimum circulation. （iii） The residual circulation at the guide vane outlet needs to be considered for the inlet boundary condition of the outlet conduit, and the value of the circulation may be measured in a specially designed test model.
基金the National Natural Science Foundation of Hunan Province,No. 06JJ4022
文摘Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（lactic-co-glycolic acid） （PLGA） copolymer to construct a three-dimensional （3D） bionic nerve conduit, with two channels and multiple microtubule lumens, and incorporating two neurotrophic factors, each with their own delivery system, as a novel environment for peripheral nerve regeneration. The efficacy of this conduit in repairing a 1.5 cm sciatic nerve defect was compared with PLGA-alone and PLGA-microfilament conduits, and autologous nerve transplantation. Results showed that compared with the other groups, the 3D bionic nerve conduit had the fastest nerve conduction velocity, largest electromyogram amplitude, and shortest electromyogram latency. In addition, the nerve fiber density, myelin sheath thickness and axon diameter were significantly increased, and the recovery rate of the triceps surae muscle wet weight was lowest. These findings suggest that 3D bionic nerve conduits can provide a suitable microenvironment for peripheral nerve regeneration to efficiently repair sciatic nerve defects. p
文摘The relationship between the head loss and the discharge and circulation of the conduit of a pump system with low head is an important problem with an obvious influence on the improvement of its hydraulic performance. The velocity circulation from the pump guide vane makes the relationship more complicated, which has to be understood comprehensively. The results indicate that, under the condition of zero circulation, the head loss of the inlet and outlet conduits is in proportion to the square of discharge. Under the condition that the Reynolds number is satisfied with the resistant square area, the conduit loss is in proportion to the square of discharge for the similar working points with different speeds in a certain rotational speed range, indicating that the pump system efficiency is constant. The outlet conduit loss of design discharge for a pump system with low head depends on the velocity circulation from the guide vane exit, and the relationship between the loss and the circulation is an open curve with an upward direction, meaning that there is an optimal circulation for the loss. Under the condition of various working points for a pump system with low head, the head loss of the outlet conduit is under the cross influence of both the discharge and the circulation. As a result, the relationship between the head loss and the discharge is almost linear, and the mechanism needs to be further studied.
基金supported by the National Natural Science Foundation of China,No.82202718the Natural Science Foundation of Beijing,No.L212050the China Postdoctoral Science Foundation,Nos.2019M664007,2021T140793(all to ZL)。
文摘Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.
基金supported by the Lorenz B?hler Fonds,#2/19 (obtained by the Neuroregeneration Group,Ludwig Boltzmann Institute for Traumatology)the City of Vienna project ImmunTissue,MA23#30-11 (obtained by the Department Life Science Engineering,University of Applied Sciences Technikum Wien)。
文摘Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.
基金Supported by the Technological innovation project of Shapingba District,No.2024111the Research Promotion Fund of Chongqing University Cancer Hospital,No.2023nlts008.
文摘BACKGROUND Type 2 diabetes(T2D)remission has been widely reported after bariatric surgery,but rarely reported after esophagectomy.AIM To explore the incidence and predictors of T2D remission 1 year after esophagectomy with gastric conduit reconstruction.METHODS In this prospective study,consecutive patients from 2 tertiary hospitals who had esophageal cancer and T2D and underwent esophagectomy with gastric conduit reconstruction were studied preoperatively and at 3 months,6 months,and 12 months postoperatively.Remission of T2D is defined as glycated hemoglobin(HbA1c)values below 6.5%without glucose-lowering medications.Related clinical information were recorded and analyzed.RESULTS A total of 187 patients were included.Of these patients,24(12.8%)discontinued antidiabetic drugs and maintained HbA1c values below 6.5%1 year after surgery.At baseline,patients with T2D remission were younger(63.0±5.2 years vs 67.0±6.1 years,P=0.002),had higher body mass index values(body weight 68.6±11.1 kg vs 61.2±9.3 kg,P=0.001;body mass index 25.5±2.4 kg/m2 vs 23.8±3 kg/m2,P=0.011),shorter duration of T2D(4.9±3.9 years vs 7.1±3.7 years,P=0.008)and higher preoperative HbA1c(8.5%±1.7%vs 7.7%±1.3%,P=0.042).Multivariate logistic regression analysis showed that younger age and greater body weight were independent predictors of T2D remission after surgery.CONCLUSION This study reveals a significant incidence of T2D remission after esophagectomy with gastric conduit reconstruction,and remission is more frequent in patients with younger age and greater body weight.
文摘Traumatic peripheral nerve injuries are a major contributor to long-term disability,accounting for nearly half of all peripheral nervous system disorders.Although autologous nerve grafting remains the clinical gold standard,it is limited by donor-site morbidity and often fails to achieve full functional recovery.Biodegradable collagen conduits have emerged as an appealing alternative,providing a scaffold for directed axonal growth without requiring graft harvest.We reported three cases of chronic nerve injuries(6-12 months post-trauma):two involving 2.0-3.5 cm ulnar nerve defects in the forearm and one with a 2.5 cm median nerve defect at the wrist.Under microscopic guidance,each defect was bridged with a tubular type I collagen conduit secured by epineurial sutures,followed by standardized physiotherapy and sensory reeducation.At 12-18 months of follow-up,all patients demonstrated near-complete sensory recovery—two-point discrimination and Semmes-Weinstein thresholds returned to≤6 mm—and motor function improved to Medical Research Council grades 4-5,restoring fine dexterity and grip strength.Patient-reported measures indicated marked reductions in neuropathic pain and paresthesia.No conduit-related adverse events or neuroma formation were observed.This case series highlights the potential of collagen-based conduits to promote robust axonal regeneration and functional restoration even in delayed presentations.By eliminating donor-site morbidity and simplifying the reconstructive procedure,conduit-assisted repair offers a less invasive,reproducible alternative to autologous grafts for both acute and chronic peripheral nerve injuries.
基金supported by the National Natural Science Foundation of China,No.30872898,81371116the Natural Science Foundation of Beijing,No.7132173
文摘Microspheres containing nerve growth factor for sustained release were prepared by a compound method, and implanted into chitosan conduits to repair 10-mm defects on the right buccal branches of the facial nerve in rabbits. In addition, chitosan conduits combined with nerve growth factor or normal saline, as well as autologous nerve, were used as controls. At 90 days post-surgery, the muscular atrophy on the right upper lip was more evident in the nerve growth factor and normal sa- line groups than in the nerve growth factor-microspheres and autologous nerve groups. Electro- physiological analysis revealed that the nerve conduction velocity and amplitude were significantly higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. Moreover, histological observation illustrated that the di- ameter, number, alignment and myelin sheath thickness of myelinated nerves derived from rabbits were higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. These findings indicate that chitosan nerve conduits com- bined with microspheres for sustained release of nerve growth factor can significantly improve facial nerve defect repair in rabbits.
基金supported by the Science and Technology Development Program of Jilin Province in China,No.20110492
文摘The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data comparing the biomechanical factors related to the sciatic nerve are available. In the present study, rabbit models of 10-mm sciatic nerve defects were prepared. The rabbit models were repaired with autologous nerve, a polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells, or a polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel. After 24 weeks, mechanical testing was performed to determine the stress relaxation and creep parameters. Following sciatic nerve injury, the magnitudes of the stress decrease and strain increase at 7,200 seconds were largest in the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel group, followed by the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells group, and then the autologous nerve group. Hematoxylin-eosin staining demonstrated that compared with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells group and the autologous nerve group, a more complete sciatic nerve regeneration was found, including good myelination, regularly arranged nerve fibers, and a completely degraded and resorbed conduit, in the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel group. These results indicate that bridging 10-mm conduit ＋ bone marrow mesenchymal stem sciatic nerve defects with a polylactic glycolic acid cells ＋ extracellular matrix gel construct increases the stress relaxation under a constant strain, reducing anastomotic tension. Large elongations under a constant physiological load can limit the anastomotic opening and shift, which is beneficial for the regeneration and functional reconstruction of sciatic nerve. Better regeneration was found with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells ＋ extracellular matrix gel grafts than with the polylactic glycolic acid conduit ＋ bone marrow mesenchymal stem cells grafts and the autologous nerve grafts.
基金supported by 973 Program(2007CB411408)National Natural Science Foundation of China(NSFC) projects (40730420 and 40973038)Chinese Academy of Sciences(KZCX2-YW-Q04)
文摘The three most crucial factors for the formation of large and super-large magmatic sulfide deposits are： （1） a large volume of mantle-derived mafic-ultramafic magmas that participated in the formation of the deposits; （2） fractional crystallization and crustal contamination, particularly the input of sulfur from crustal rocks, resulting in sulfide immiscibility and segregation; and （3） the timing of sulfide concentration in the intrusion. The super-large magmatic Ni-Cu sulfide deposits around the world have been found in small mafic-ultramafic intrusions, except for the Sudbury deposit. Studies in the past decade indicated that the intrusions hosting large and super-large magmatic sulfide deposits occur in magma conduits, such as those in China, including Jinchuan （Gansu）, Yangliuping （Sichuan）, Kalatongke （Xinjiang）, and Hongqiling （Jilin）. Magma conduits as open magma systems provide a perfect environment for extensive concentration of immiscible sulfide melts, which have been found to occur along deep regional faults. The origin of many mantle-derived magmas is closely associated with mantle plumes, intracontinental rifts, or post-collisional extension. Although it has been confirmed that sulfide immiscibility results from crustal contamination, grades of sulfide ores are also related to the nature of the parental magmas, the ratio between silicate magma and immiscible sulfide melt, the reaction between the sulfide melts and newly injected silicate magmas, and fractionation of the sulfide melt. The field relationships of the ore-bearing intrusion and the sulfide ore body are controlled by the geological features of the wall rocks. In this paper, we attempt to demonstrate the general characteristics, formation mechanism,tectonic settings, and indicators of magmatic sulfide deposits occurring in magmatic conduits which would provide guidelines for further exploration.
基金supported by grants from the National Program on Key Basic Research Project of China(973 Program),No.2014CB542200Program for Innovative Research Team in University of Ministry of Education of China,No.IRT1201+1 种基金the National Natural Science Foundation of China,No.31271284,31171150,81171146,30971526,31100860,31040043,31371210Program for New Century Excellent Talents in University of Ministry of Education of China,No.BMU20110270
文摘The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph-eral nerve injury are better than in the traditional epineurium suture,so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury.This study sought to identify the regeneration law of nerve fibers in the biological conduit.A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit.The results showed that the biological conduit had good his-tocompatibility.Tissue and cell apoptosis in the conduit apparently lessened,and regenerating nerve fibers were common.The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture.During the prime period for nerve fiber regeneration(2-8 weeks),the number of Schwann cells and nerve fibers was higher in both proximal and distal ends,and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture.The above results provide an objec-tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.
基金supported by the National Key R&D Program of China,No.2017YFA0104701(to YW)the National Natural Science Foundation of China,No.31771052(to YW)+1 种基金the Natural Science Foundation of Beijing of China,No.7172202(to YW)the PLA Youth Training Project for Medical Science of China,No.16QNP144(to YW)
文摘In recent years, the use of Schwann cell transplantation to repair peripheral nerve injury has attracted much attention. Animal-based studies show that the transplantation of Schwann cells in combination with nerve scaffolds promotes the repair of injured peripheral nerves. Autologous Schwann cell transplantation in humans has been reported recently. This article reviews current methods for removing the extracellular matrix and analyzes its composition and function. The development and secretory products of Schwann cells are also reviewed. The methods for the repair of peripheral nerve injuries that use myelin and Schwann cell transplantation are assessed. This survey of the literature data shows that using a decellularized nerve conduit combined with Schwann cells represents an effective strategy for the treatment of peripheral nerve injury. This analysis provides a comprehensive basis on which to make clinical decisions for the repair of peripheral nerve injury.
